500 – 700 million years ago, even before dinosaurs roamed the Earth, jellyfish were drifting along on ocean currents. Jellies are among the most spectacular and mysterious marine species in the world. They are the oldest multi-organ animal and have morphed into more than 2,000 different jellyfish species. Some live in freshwater, but jellies can be found in every ocean. Some sea jellies survive close to the surface while others dwell in extreme depths, glowing with bioluminescence in the pitch black water near the bottom of the ocean. Many scientists and deep ocean explorers expect to discover countless more beautiful jiggly jellyfish as they explore deep sea canyons, and other extreme water conditions near underwater volcano vents and in the harsh frozen temperatures of arctic waters. [72 Photos]

Jellyfish go with flow and have drifted along on ocean currents for millions of years, even before dinosaurs lived on the Earth. Few marine creatures are as mysterious and intimidating as jellyfish. Though easily recognized, these animals are often misunderstood. Sea nettles often have riders on their bodies, sometimes offering a place for small living organisms to be able to move around and sometimes being the food source for the organism. There is a reddish tint on the bell of the Pacific Sea Nettle or West Coast Sea Nettle which can span over 3 feet. This is a distinctive characteristic along with maroon tentacles that identify this particular species of jellyfish. The tentacles can be up to 15 feet long. Photo #1 by luna

Inside the bell or umbrella-shaped body is the mouth opening and jellyfish tentacles hang down from gelatinous bodies. They use the stinging cells of their tentacles to stun or paralyze their prey before they eat it. Jellies mostly float on ocean currents, but if a jellyfish squirts water from its mouths, then it can propel forward. Photo #2 by animaltheory

If there are aliens on our planet, it might be NOAA, and not NASA, to discover that in the unexplored depths of our oceans . . . this summer one leading British space scientists claimed aliens do exist and they look similar to huge jellyfish. Photo #4 by NOAA’s National Ocean Service

This is a “Mauve Stinger” in Australia, but the most feared jellyfish in Australian waters is the box jellyfish. It is “the most venomous marine animal known to mankind and its sting is often fatal.” Photo #5 by animaltheory

The National Science Foundation funds and manages the U.S. Antarctic Program, which supports research in aeronomy and astrophysics, biology and medicine, geology and geophysics, glaciology, and ocean and climate systems. (Date of Image: Oct. 14, 2005) Diplulmaris antarctica‎. Photo #7 by Henry Kaiser, National Science Foundation

Crown Jellyfish “are distinguished from other jellyfish by the presence of a deep groove running around the umbrella, giving them the crown shape from which they take their name. Many of the species in the order inhabit deep sea environments.” Photo #8 by Bing

Sea Jellies Gallery from Manila Ocean Park. Although jellies are soft-bodied and lack a skeleton, making fossils rare, evidence suggests that jellyfish predate dinosaurs by some 400 million years. Photo #9 by FoxyReign

Papuan Jellyfish (Mastigias papua) in a special exhibit at the Monterey Bay Aquarium. This aquarium also has a huge bioluminescence and fluorescence jellies exhibit. Photo #10 by Stevenj

A flotilla of fish follow a transparent drifting jellyfish, Aurelia aurita. The stingers in its tentacles have toxins in them. A jellyfish will sting anything that comes in contacts with including other creatures in the water and even humans. The sting of different jellies have different toxicity levels. Photo #11 by Sonke Johnson / NOAA Office of Ocean Exploration

The National Oceanic & Atmospheric Administration (NOAA) and its ancestor agencies have been exploring the sea for about 180 years now. One such expedition to the hidden realms and canyons of the sea discovered this jellyfish during “Voyage To Inner Space – Exploring the Seas With NOAA.” Photo #12 by Anna Fiolek, NOAA Central Library

Cassiopea is also called the upside-down jellyfish. The “mild” stings are notorious for being extraordinarily itchy, appearing in the form of a red rash-like skin irritation. When there are a group of jellies, it is called swarm or a smack. Photo #14 by Jacopo Werther

Moon jellyfish in the Pairi Daiza aquarium in Belgium. This is one of the most common jellyfish that people see in aquariums around the globe. If stung by the moon jelly, it is only slightly venomous. Contact can produce symptoms from immediate prickly sensations to a mild burning pain. Photo #16 by Luc Viatour / www.Lucnix.be

Mediterranean jellyfish. The Cassiopeia Mediterranean species reaches 30 cm in diameter and has numerous short tentacles. Photo #27 by Intandem

Olindias formosa at Osaka Aquarium. The “flower hat jelly can grow to be about 15 cm (6 inches) in diameter. Its sting is painful but non-lethal to humans. Its diet consists mostly of small fish.” Photo #28 by KENPEI

NOAA Expedition to the Deep Slope. The Sea Nettle is semi-transparent and has small whitish dots and reddish-brown stripes. In some cases, these stripes and dots are missing, and they make the sea nettle look whitish and opaque. The sea nettle is saucer-like in shape. The bell of the sea nettle usually grows to about 6 to 8 inches in diameter. It also has four oral arms attached to the underside of the mouth. In addition to this, it has a number of long tentacles, along the margins of its body, which extend for several feet. Photo #29 by Anna Fiolek/ Expedition to the Deep Slope 2007, NOAA OE

Left: The Smithsoian Ocean Portal writes, “A “pink meanie” jellyfish (Drymonema larsoni)—a species found in the Gulf of Mexico and the Caribbean—feeds on a moon jelly (Aurelia). Dr. Keith Bayha from the Dauphin Island Sea Lab and Dr. Michael Dawson from the University of California, Merced recently discovered that the pink meanie represents not only a new species, but an entirely new family of jellyfish.” Right: NOAA’s “The Hidden Ocean, Arctic 2005: The new jellyfish is in the order Narcomedusae. It has four tentacles, 12 stomach pouches, and most interestingly, four small secondary tentacles at the very edge of the bell. While foraging for food, this species holds its long tentacles, covered with poison filled stinging cells, out in front while it swims, perhaps to ambush its prey more effectively.” Photo #30 by Mary Elizabeth Miller, Dauphin Island Sea Lab & #31 by Kevin Raskoff, California State University, Monterey Bay

Top: Sea Nettle Jelly, Jellyfish, Monterey Bay Aquarium, California. Bottom: Black Sea Nettle (“Chrysaora Achlyos”). They have four oral arms; long marginal tentacles hang from the bell and can extend several feet. Symptoms from sea nettle stings often are described as burning rather than stinging and are considered moderate to severe. Exercise caution if sea nettles are observed in the water, and do not swim if large numbers are present. The carnivorous Black Sea Nettle is a ‘giant’ among jellyfish with its bell measuring up to 3 feet (1 m) in size, and its arms extending up to 20 ft (6 m) in length. Photo #42 by Fred Hsu & #43 by Fred Hsu & #44 by Jim G

Underwater World, Singapore. The Smithsonian reported, “GFP, a green fluorescent protein found in crystal jellies, has important medical applications. Mayo Clinic scientists recently inserted a version of GFP and a gene from a rhesus macaque known to block a virus that causes feline AIDS into a cat’s unfertilized eggs. When the kittens were born, they glowed green in ultraviolet light, indicating that the gene was successfully transferred. Biologist Osamu Shimomura won a Nobel Prize in Chemistry in 2008 for discovering GFP.” Photo #45 by Schristia

“Purple-striped Jelly” (Chrysaora Colorata) taken at Monterey Bay Aquarium, Monterey, California, USA. The Scyphozoa class, within the phylum Cnidaria, are sometimes referred to as the ‘true jellyfish’.” Photo #46 by Sanjay Acharya

Left: This tiny and very dangerous Portugese Man-O-War was collected using a dip net over the rail of the R-V Seward Johnson during one evenings “night-lighting” samplings. Its sting is said to be as toxic as a cobra’s bite. Although NOAA has it listed as a jellyfish, it looks exactly like a jellyfish and is potentially deadly, but is actually not a true jellyfish. It is in fact a Siphonophorae, which is a collection of multiple organisms. The tentacles are a separate creature to the gas bladder, for example, and their tentacles can be as long as 45 metres or more. Whilst they can inflect painful stings on humans that, in some rare cases, results in death, some animals such as the Clownfish can swim amongst the normally lethal tentacles with impunity. Center: Porpida porpida has a small disc like body and floats freely in the water column. Related to other species of jellyfish, this species measures just one inch in diameter. Right Top: Tiny jellyfish at Port of Nagoya Public Aquarium. Right Bottom: Jellyfish Bicol. Photo #49 by Bruce Moravchik, NOAA & #50 by Bruce Moravchik, NOAA & #51 by “KIUKO” & #52 by Andrew MacLeod

“Dance in light.” The life span and maximum size varies by jelly species. Jellyfish held in public aquariums are carefully tended, fed daily even when food might be seasonally rare in the wild, and sometimes treated with antibiotics if they develop infections, so may live several years, though this would be very unusual in the sea. Most large coastal jellyfish live 2 to 6 months, during which they grow from a millimeter or two to many centimeters in diameter. Photo #53 by Donnie Nunley

Left: The lion’s mane jellyfish (Cyanea capillata) is also know as the winter jelly because the lion’s mane typically appears during colder months of the year. Found in the north Atlantic, they have a bell which can reach six feet (two meters) in diameter with tentacles as long as 100 feet (33 meters). Cyanea are generally considered moderate stingers. Symptoms are similar to those of the moon jelly but, usually more intense. Pain is relatively mild and often described as burning rather than stinging. Right: Giant Normura’s Jellyfish invading Japan. “Pitting two hands against thousands of stinging tentacles, a diver attaches a tracking device to a giant Nomura’s jellyfish off the coast of Japan on October 4, 2005.” The 450 pounds and seven feet long Nomura jellies have plagued Japan. This jelly is about the size of a sumo wrestler, but it’s smaller when compared to the cold-water lion’s mane jellyfish that can reach over 100 feet long with 1,000 stinging tentacles. Photo #58 by Dan Hershman & #59 by DazzlingFacts & $60 by Yomiuri Shimbun

These moon jellyfish would fit right in on one underground level of Skyrim. Wikipedia explains, “The medusa is translucent, usually about 25–40 cm in diameter, and can be recognized by its four horseshoe-shaped gonads that are easily seen through the top of the bell.” They are called Aurelia Aurita, Saucer Jelly and Common Jelly. Photo #62 by dark side of the moon

Australian Box Jellyfish is listed as #3 in the deadliest animals on the planet, even more so that #4 the Great White shark. The box jelly is the most venomous marine animal known to mankind. It transparent and pale blue in color, which makes it pretty much invisible in the water. For a long time, nobody knew what was causing swimmers such excruciating pain and sometimes killing them. Also called the Sea Wasp, these jellies are strong, graceful swimmers. The box jelly can grow up to 5-6 inches in diameter and 4-6 inches in height. Photo #63 by realwallpapers & #64 by trywalkingwithghosts & #65 by ReasearchScience

2.5 cm long Antarctic Transparent Jellyfish. Jellies reproduce both sexually and asexually. Upon reaching adult size, jellyfish spawn daily if there is enough food. In most species, spawning is controlled by light, so the entire population spawns at about the same time of day, often at either dusk or dawn. Photo #66 by aminaltheory

Medusa — Queen Jellyfish. Some jellyfish like blubber jellies are edible and considered a delicacy in parts of Asia. Photo #67 by jekrub

Jellyfish are made up of more than 95% water. Their gelatin-soft bodies lack a skeletal structure or outer shell. They are delicate and easily damaged. Jellyfish die when removed from the water, but if you step on a dead jelly, it can still sting you. Photo #70 by goodfon

Most jellyfish live from a few hours to a few months, but there is a species of jelly called Turritopsis nutricula that may be immortal. The jelly reportedly can play its life-cycle in reverse, transforming from an adult medusa back to an immature poly. Photo #71 by Stella31

Since jellyfish are not actually fish, some people consider the term jellyfish a misnomer. American public aquariums have popularized the terms jellies or sea jellies. Photo #72 by Victor Amor